1. Field of the Invention
The present invention relates to straining and filtering devices, and more particularly to a suction strainer for use with a centrifugal pump for pumping a fluid from a source to another location.
2. Background of the Invention
Centrifugal pumps are widely used for pumping fluids, such as environmental water, from a body of fluid (source) at one location to another location for a variety of purposes including irrigation of crops, flood control, land drainage, etc. Typically, a suction hose is positioned in a body of water with the strainer connected to the hose end. The strainer permits water to pass therethrough with very little resistance but inhibits the passage of debris greater than a desired size. Such debris can restrict or block the fluid line reducing pumping performance and potentially leading to pump seizure and/or damage.
In the prior art, suction strainers generally comprise a basket-shaped cage having an open end and a threaded connection at the other end for connecting thereto a hose fitting. A removable cover is securely placed on the open end. The cage and the cover have openings or passages which allow the fluid to flow into the cage. To use the strainer, a hose fitting having threads at its one end that compliment the threads in the cage is screwed into the cage. One end of the hose is connected to the second end of the hose fitting while the other end of the hose is fitted onto the centrifugal pump. To transfer fluid from a source to another location, the strainer is placed in the body of fluid and the pump is operated. The fluid enters the strainer and is passed into the hose and thus the pump. The openings in the cage and the cover prevent debris of sizes greater than the openings from entering the strainer and thus the pump.
Various hose sizes are used for different applications. To provide strainers for different hose sizes, the strainer manufacturers make a separate cage having a threaded hose fitting connection for each hose size. Hose diameters vary in size depending upon the pump size and the hose used. Hoses are generally available from sizes smaller than one inch in diameter to greater than four inches. The cages and the covers are typically injection-molded parts. Thus, the strainer manufacturers make a separate cage mold having a threaded connection therein for each hose size. The manufacturers and distributors also must inventory a strainer and a separate hose fitting for each hose size.
Applicant has noticed significant drawbacks in such prior art strainer design: specifically, the use of a threaded connection for attachment of the hose fitting and the use of a separate hose fitting. The use of a threaded connector increases the cost of building the injection molds and the cost of manufacturing the cage due to increased molding discontinuities at the threaded end. In addition, such prior art strainers consist of three separate parts which must be made and inventoried. Clearly, a strainer design which has fewer parts and which is less expensive to make by eliminating the threaded connector would be economical and, thus, desirable.
The present invention addresses the above-noted problems and provides a strainer having two parts: a cage that may be used with multiple hose sizes and a cover that has a hose connection thereon.